Method of managing trunk and querying and ascertaining ring-back sound to provide ring-back sound in subscriber-based ring-back sound service

ABSTRACT

The present invention relates to a method of managing a trunk, and querying and ascertaining a ring-back sound to provide the ring-back sound in a subscriber-based ring-back sound service. In the trunk management method, a terminating mobile switching center ( 32 ) requests the intelligent peripheral ( 50 ) to release a trunk call when the terminating mobile switching center recognizes the answer of the terminating subscriber or when a first predetermined period of time has elapsed from a time when it is recognized that a corresponding ring-back sound is provided to the originator. Further, the intelligent peripheral ( 50 ) requests the terminating mobile switching center ( 32 ) to release the trunk call when a second predetermined period of time has elapsed from a time when the ring-back sound is provided.

TECHNICAL FIELD

The present invention relates, in general, to a method of managing atrunk to provide a ring-back sound in a subscriber-based ring-back soundservice, and more particularly, to a method of managing a trunk betweena mobile switching center and an intelligent peripheral as a channelrequired to provide a ring-back sound in a subscriber-based ring-backsound service for improving a conventional uniform ring-back toneproviding method by providing a terminating subscriber's desiredspecific sound as the ring-back sound that substitutes for a typicalring-back tone. In addition, the present invention relates to a methodof querying an intelligent peripheral server about a ring-back sound ofa corresponding terminating subscriber (that is, the specific sound) bythe intelligent peripheral having a plurality of ring-back sounds when asubscriber-based ring-back sound service is provided to improve aconventional uniform ring-back tone providing method by providing aterminating subscriber's desired specific sound as a substitute for aring-back tone on the basis of the trunk management method. In addition,the present invention relates to a method of ascertaining a ring-backsound of a corresponding subscriber or another subscriber as a specificsound when a subscriber-based ring-back sound service is provided toimprove a conventional uniform ring-back tone providing method byproviding a terminating subscriber's desired specific sound as asubstitute for a ring-back tone.

RELATED ART

Generally, there is adopted a method in which, if an originator attemptsto place a call over a conventional mobile communication network, amobile switching center of a terminating subscriber provides a uniformring-back tone to the originator. However, such a conventional ring-backtone providing method is problematic in that, since the mobile switchingcenter provides a uniform tone, the originator cannot determine whethera connection error occurs until the terminating subscriber answers, and,additionally, a service for providing various sounds corresponding tothe characteristics of the users, instead of the uniform ring-back tone,cannot be provided

Recently, a method of providing various pieces of advertising sounds,instead of the above-described uniform ring-back tone, has beenproposed. However, this method is implemented in such a way that itprovides a specific advertising sound selected by a communicationnetwork service provider to an originator without the right of choice ofa subscriber, and then enables the originator to call without charge fora predetermined period of time after that Therefore, this method is alsoproblematic in that the originator cannot determine whether a connectionerror occurs until a terminator answers, and, additionally, a servicefor providing various sounds corresponding to the characteristics ofusers, instead of the uniform ring-back tone, cannot be provided.

In order to solve these problems, a subscriber-based ring-back soundservice method of providing a specific sound registered or selected by aterminating subscriber to an originator, instead of a typical ring-backtone, was proposed by the present applicant, which is described withreference to FIG. 1.

FIG. 1 is a flowchart of a conventional subscriber-based ring-back soundservice method If an arbitrary originator requests a call connection bydialing a subscriber of the subscriber-based ring-back sound service(hereinafter, referred to as a terminating subscriber), a correspondingOriginating Mobile Switching Center (O_MSC) 31 requests terminatinglocation information from a Home Location Register (HLR) 10 (locationrequest) at step S101.

The HLR 10 requests routing information from a terminating MSC (T_MSC)32 in response to the request (routing request) at step S102. The T_MSC32 responds to the routing request by providing the routing information(that is, Temporary Local Directory Number: TLDN) to the HLR 10 at stepS103.

The HLR 10 responds to step S101 by sending the routing information tothe O_MSC 31 at step S104. Therefore, the O_MSC 31 requests theconnection of a trunk (or designated as Integrated Services DigitalNetwork User Part: ISUP) call from the T_MSC 32 on the basis of therouting information, thereby establishing a traffic channel between theO_MSC 31 and the T_MSC 32 at step S105.

Then, the T_MSC 32 checks a state of the terminating subscriber usingradio paging when receiving the ISUP call connection request at stepS105 at step S106. When a response to the paging is received from acorresponding terminating terminal (not shown) at step S107, the T_MSC32 determines whether the terminator is a service subscriber and whetherthe service is activated if the terminator is a service subscriber withreference to service setting information stored in the T_MSC 32. In thiscase, if the terminator is the service subscriber and the service isactivated, the T_MSC 32 requests an ISUP call connection from anintelligent peripheral 50 to establish a traffic channel between theT_MSC 32 and the intelligent peripheral 50, and to provide terminatingand originating phone numbers to the intelligent peripheral 50 at stepS108.

As a result of the above operation, traffic channels are establishedamong the O_MSC 31, the T_MSC 32 and the intelligent peripheral 50.

The intelligent peripheral 50 requests a ring-back sound code from anintelligent peripheral server 70 on the basis of the originating andterminating phone numbers at step S109. The intelligent peripheralserver 70 responds to step S109 by searching for the ring-back soundcode preset in connection with the originating and terminating phonenumbers according to the request and sending the searched ring-backsound code to the intelligent peripheral 50 at step S110. Theintelligent peripheral 50 transmits a ring-back sound corresponding tothe received ring-back sound code instead of a ring-back tone to theoriginator through the traffic channel at step S111.

If the terminating subscriber answers the call while the ring-back soundis transmitted instead of the ring-back tone as described above, andthen the T_MSC 32 recognizes the answer of the terminating subscriber,the T_MSC 32 requests the release of the ISUP call from the intelligentperipheral 50 to allow the intelligent peripheral 50 to release the callat step S112. Simultaneously, the T_MSC 32 enables telephoneconversation between the originator and the terminating subscriberthrough the traffic channel established between the T_MSC 32 and theO_MSC 31 at step S113.

However, in the above-described subscriber-based ring-back sound servicemethod, the MSCs generally limit a time for which a typical ring-backtone is transmitted to a preset time. Therefore, the conventionalservice method is problematic in that, if the preset time is longer thana time for which a ring-back sound stored in the intelligent peripheralis played, muting occurs for the time difference between them, thuscausing the originator to recognize the muting rough the originatingmobile terminal.

In the mean time, when a specific function is performed for the purposeof trunk management the saving of bunk resources is a key point.

However, since the number of subscribers is small when initiating theservice, one or a few intelligent peripherals 50 are located in thecenter of a service area, and a plurality of MSCs 31 and 32, distributedacross the country, share one or a few intelligent peripherals 50.Therefore, there is a problem in that, as the number of subscribersincreases, a phenomenon in which the plurality of MSCs concentricallyand excessively occupy trunk resources connected to the one or a fewintelligent peripherals may occur, thereby causing a serviceinterruption.

Further, in order for a subscriber to ascertain his or her own ring-backsound or a another subscriber' ring-back sound in the above-describedsubscriber-based ring-back sound service method, the subscriber musthear a ring-back sound provided instead of a typical ring-back tone, asin the case of the procedure of step S109, by placing a call to acorresponding subscriber using a desired ring-back sound.

Therefore, the above-described service method is disadvantageous inthat, even though a user only desires to ascertain a ring-back soundwithout placing a call, unnecessary trunk resources are occupied andthen wasted from the standpoint of the network, and unnecessarytelephone conversation is made from the standpoint of the subscriber.

DISCLOSURE OF THE INVENTION

Accordingly, the present invention has been made keeping in mind theabove problems occurring in the prior ark and an object of the presentinvention is to provide a method of managing a trunk to provide aring-back sound in a subscriber-based ring-back sound service, whichprevents muting.

Another object of the present invention is to provide a method ofquerying a ring-back sound in a subscriber-based ring-back soundservice, which allows a mobile switching center to access an intelligentperipheral located closest thereto without passing through a gateway soas to save trunk resources when the subscriber-based ring-back soundservice is provided, thus preventing mobile switching centers fromexcessively occupying trunk resources.

A further object of the present invention is to provide a method ofascertaining a ring-back sound in a subscriber-based ring-back soundservice, which enables a subscriber to ascertain his or her ownring-back sound or another subscriber's ring-back sound withoutoccupying unnecessary trunk resources or without placing a call in thesubscriber-based ring-back sound service.

In order to accomplish the above object, the present invention providesa method of managing a trunk to provide a ring-back sound in asubscriber-based ring-back sound service, the ring-back sound servicemethod including the steps of a) a home location register providingfirst information indicating whether a ring-back tone preset in the homelocation register is substituted and second information for performingrouting to intelligent peripheral means to a corresponding terminatingmobile switching center when a location of a terminating subscriber isregistered; b) the terminating mobile switching center providing aring-back tone to an arbitrary originator or requesting a connection ofa trunk call from the intelligent peripheral means according to thefirst and second information, when the terminating mobile switchingcenter recognizes a call connection request transmitted from thearbitrary originator to the terminating subscriber; c) the intelligentperipheral means searching for a ring-back sound preset with respect tothe terminating subscriber after connecting the trunk call in responseto the trunk call connection request, and providing the searchedring-back sound to the originator instead of the ring-back tone throughthe trunk-connected terminating mobile switching center, the trunkmanagement method comprises the steps of the terminating mobileswitching center requesting a release of the connected trunk call fromthe intelligent peripheral means when an answer of the terminatingsubscriber is recognized or when a first predetermined period of timehas elapsed from a time when it is recognized that the searchedring-back sound is provided to the originator; and the intelligentperipheral means requesting a release of the connected trunk call fromthe terminating mobile switching center when a second predeterminedperiod of time has elapsed from a time when the ring-back sound beginsto be provided.

Preferably, the first and second predetermined period of times are setin consideration of a ring-back tone transmission time preset in theterminating mobile switching center, and a length of the ring-backsound. Preferably, the length of the ring-back sound is an averagelength of all ring-back sounds included in the intelligent peripheralmeans. Preferably, the second predetermined period of time is set to beequal to or longer than the first predetermined period of time.

Further, the present invention provides a method of querying a ring-backsound in a subscriber-based ring-back sound service, in which routingfrom at least one intelligent peripheral to at least one intelligentperipheral server is performed to query a ring-back sound in asubscriber-based ring-back sound service process, the intelligentperipheral being constructed in such a way that a plurality ofintelligent peripherals are installed according to mobile switchingcenters or mobile switching center groups to allow one or more adjacentmobile switching centers to be directly trunk-connected to one of theintelligent peripherals according to singular routing information, andthe intelligent peripheral server being constructed in such a way thatring-back sound codes corresponding to ring-back sounds stored in theintelligent peripherals are stored in the intelligent peripheral serverto be preset and registered according to subscribers, and a plurality ofintelligent peripheral servers are installed according to phone numbersof subscriber terminals, prefix numbers thereof, prefix number groupsthereof, or main working areas of the subscribers to correspond toinformation of the subscribers, the method comprising the steps of a)when a request for a trunk call connection that allows a ring-back soundpreset and registered with respect to a terminating terminal to betransmitted to an originating terminal instead of a typical ring-backtone according to routing information to a corresponding intelligentperipheral provided from the home location register, is received from acorresponding mobile switching center, the corresponding intelligentperipheral searching for routing information to one among the pluralityof intelligent peripheral servers depending on information of theterminating subscriber provided from the trunk-connected correspondingmobile switching center, and b) the corresponding intelligent peripheralperforming routing to the corresponding intelligent peripheral serverdepending on the searched routing information and querying and obtaininga code of a corresponding ring-back sound depending on the informationof the terminating subscriber.

Further, the present invention provides a method of ascertaining aring-back sound in a subscriber-based ring-back sound service, whichallows a subscriber to ascertain his or her own ring-back sound oranother subscriber's ring-back sound substituting for a typicalring-back tone using an automatic response service unit having a varietyof ring-back sounds as specific sounds to correspond to code informationwhen the subscribed-based ring-back sound service for providing aterminating subscriber's desired specific sound instead of the ring backtone is implemented, the automatic response service unit performing thesteps of a) obtaining information of an arbitrary second subscriberusing a ring-back sound to be ascertained while communicating with amobile terminal of a first subscriber connected to the automaticresponse service unit through a mobile communication network dependingon a preset scenario; b) requesting and obtaining code informationcorresponding to the second subscriber information from an intelligentperipheral server while communicating with the intelligent peripheralserver having the code information to correspond to the subscriberinformation; and c) transmitting a ring-back sound provided tocorrespond to the obtained code information to the mobile terminal ofthe first subscriber.

Preferably, the ring-back sound may further comprise the step of d)changing code information corresponding to the first subscriberinformation to code information corresponding to the second subscriberinformation while communicating with the intelligent peripheral server,when a request for change of the transmitted ring-back sound is receivedfrom the mobile terminal of the first subscriber depending on thescenario.

Preferably, the subscriber information is a phone number of a mobileterminal of each subscriber. Preferably, the ring-back soundascertainment method may further comprise the step of authenticating thefirst subscriber depending on an originating number from the mobileterminal of the first subscriber. Preferably, the automatic responseservice unit and the intelligent peripheral server communicate with eachother through the Internet.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a flowchart of a conventional subscriber-based ring-back soundservice method;

FIG. 2 is a block diagram of a subscriber-based ring-back sound serviceappartus to which a subscriber-based ring-back sound service methodaccording to the present invention is applied;

FIG. 3 is a flowchart showing a service subscription procedure in thesubscriber-based ring-back sound service method according to the presentinvention;

FIG. 4 is a flowchart showing a service change/addition procedure in thesubscriber-based ring-back sound service method according to the presentinvention;

FIG. 5 is a flowchart showing a service cancellation procedure in thesubscriber-based ring-back sound service method according to the presentinvention;

FIG. 6 is a flowchart of a method of managing a trunk to provide aring-back sound in the subscriber-based ring-back sound service methodaccording to the present invention, wherein the trunk management methodis an actual service procedure performed after the procedures of FIG. 3and/or FIG. 4 are completed;

FIG. 7 is a view showing a format of an additional service settingmessage transmitted from a home location register to a terminatingmobile switching center in the subscriber-based ring-back sound servicemethod according to the present invention;

FIG. 8 is a flowchart of a conventional subscriber-based ring-back soundservice method using an originating mobile switching center previouslyproposed by the present applicant;

FIG. 9 is a view showing an example of a network connection among mobileswitching centers, an intelligent peripheral and an intelligentperipheral server of FIG. 2 according to the present invention;

FIG. 10 is a flowchart of a method of querying a ring-back sound in thesubscriber-based ring-back sound service method according an embodimentof the present invention;

FIG. 11 is a view showing the construction of a first database of theintelligent peripheral according to the present invention;

FIG. 12 is a view showing the construction of a database of theintelligent peripheral server according to the present invention;

FIG. 13 is a view showing the construction of a second database of theintelligent peripheral according to the present invention;

FIG. 14 is a view showing the basic construction of an apparatus forimplementing a method of ascertaining a ring-back sound in thesubscriber-based ring-back sound service on the basis of the apparatusof FIG. 2 according to an embodiment of the present invention;

FIG. 15 is a flowchart of the method of ascertaining a ring-back soundin the subscriber-based ring-back sound service according to theembodiment of the present invention;

FIG. 16 is a view showing the construction of the database of theintelligent peripheral server according to the present invention; and

FIG. 17 is a view showing the construction of the database of theintelligent peripheral according to the present invention.

DESCRIPTION OF THE NUMERALS ON THE MAIN PARTS OF THE DRAWINGS

 10: home location register 20: No. 7 network  31, 32: mobile switchingcenter 40, 90: gateway  50: intelligent peripheral 60: Internet  70:intelligent peripheral server 80: subscriber database 100: Web server55: automatic response service unit

BEST MODE FOR CARRYING OUT THE INVENTION

Reference should now be made to the drawings, in which the samereference numerals are used throughout the different drawings todesignate the same or similar components.

—Trunk Management Method—

Hereinafter, a method of managing a trunk to provide a ring-back soundin a subscriber-based ring-back sound service according to a preferredembodiment of the present invention will be described in detail withreference to the attached drawings.

FIG. 2 is a block diagram of a subscriber-based ring-back sound serviceapparatus to which a subscriber-based ring-back sound service methodaccording to the present invention is applied. As shown in FIG. 2, theservice apparatus includes a Home Location Register (HLR) 10; MobileSwitching centers (0_MSC/VLR: visitor Location Register, and T_MSC/VLR)31 and 32 communicating with the HLR 10 through a Signaling TransferProtocol (STP)-based No. 7 network 20; an Intelligent Peripheral (IP) 50connected to the No. 7 network 20 through a gateway (Cellular GatewaySystem: CGS) to communicate with both the O_MSC/VLR 31 and the T_MSC/VLR32 through the gateway 40; an IP server 70 for performing datacommunication with the IP 50 through the Internet 60; a subscriberdatabase 80 connected to the HLR 10 through the Internet 60; and a Webserver 100 connected to the Internet 60 through a gateway 90 tocommunicate with both the IP 50 and the IP server 70.

The HLR 10 has all functions as a conventional network component, andadditionally has a function of presetting and storing first informationindicating whether a ring-back tone is substituted and secondinformation for performing routing to the IP 50 as profile informationof a terminating subscriber. The profile information is preset andstored as additional service subscription information of the terminatingsubscriber profile.

The MSCs 31 and 32 have all functions as the conventional networkcomponents, and additionally have functions of receiving and storing thepreset first and second information while communicating with the HLR 10at the time of registering the location of the terminating subscriber,receiving a ring-back sound for substituting for a typical ring-backtone while communicating with the IP 50 on the basis of the first andsecond information when a call connection to the terminating subscriberis requested, and providing the received ring-back sound to acorresponding originator instead of the ring-back tone.

The IP 50 stores a variety of ring-back sounds, and is characterized inthat it is connected to the MSCs 31 and 32 through the gateway 40 andprovides the stored ring-back sound to the MSCs 31 and 32 whilecommunicating therewith.

The IP server 70 has a function of communicating with the IP 50 throughthe Internet 60 to specify the types of ring-back sounds, which the IP50 must provide to the MSCs 31 and 32, on the basis of the combinationsof identification information of terminating subscribers requested toconnect calls, identification information of originators correspondingthereto and/or time slot information when call connections arerequested. For example, various types of ring-back sounds can bespecified according to originator, originator group, originator age,gender, occupation, and/or call originating time slot and the like. Forexample, when the IP server 70 assigns respective codes to variousring-back sounds stored in the IP 50, and a terminator selectsoriginators, originator groups, call originating time slots, etc., whensubscribing to the service or changing his or her information, andspecifies ring-back sounds corresponding to the selected items, the 1Pserver 70 has a plurality of pieces of information on the specifiedring-back sounds in the form of a table. Therefore, the IP server 70controls the IP 50 to provide a corresponding ring-back sound to anoriginating MSC on the basis of the table information.

The Web server 100 is connected to the IP 50 or the IP server 70 throughthe Internet 60 to add a ring-back sound to the IP 50, or changeinformation (specific originator, originator group, call originatingtime slot, etc.) required to specify ring-back sounds by the IP server70 and ring-back sound codes corresponding thereto. Such an addition andchange function can be performed by the subscriber through a Web pageprovided from the Web server 100.

The operation of the service apparatus of FIG. 2 is described in detail.

If a terminating user, desiring to use a service that transmits aspecific ring-back sound, applies for the ring-back sound service to aservice provider to which the terminating user belongs, the terminatinguser is registered as a subscriber in the subscriber database 80 of theservice provider. The subscriber database 80 registers the terminatingsubscriber for the service in the HLR 10 which is a component within thenetwork. The HLR 10 sets a corresponding service in a subscriberdatabase provided therein. Further, the HLR 10 sends service informationobtained when a location registration procedure occurs, and routing datafor establishing a call to the IP 50, to a corresponding MSC 31 or 32currently performing a mobile service (that is, a serving MSC). TheT_MSC 32 sets the received service information and routing data incorresponding subscriber service data.

Therefore, if an originator requests a call setup from a correspondingterminating subscriber, the T_MSC 32 recognizes that a specificring-back sound transmitting service is set on the basis of the setservice information, connects a call to the IP 50 using the routingdata, and, simultaneously, informs the terminating subscriber that anincoming call is terminated (paging). At this time, the IP queries theIP server 70 which ring-back sound is set by a corresponding subscriber,in communication with the IP server 70. The IP server 70 sends a codecorresponding to a ring-back sound specified by the subscriber to the IP50. The IP 50 transmits the ring-back sound corresponding to the code tothe originator, instead of a typical ring-back tone, thus enabling theoriginator to hear the ring-back sound until the terminating subscriberanswers. When the terminating subscriber receives the incoming call, theT_MSC 32 releases a call channel established with the IP 50, andconnects the originator and the terminating subscriber to enabletelephone conversation between them.

Now, the trunk management method to provide a ring-back sound in thesubscriber-based ring-back sound service applied to the presentinvention is described in detail. In this case, since the trunkmanagement method is applied to the subscriber-based ring-back soundservice apparatus, it is described in parallel to the operation of theservice apparatus of FIG. 2.

FIG. 3 is a flowchart showing a service subscription procedure in thesubscriber-based ring-back sound service method according to the presentinvention.

If there is any request for subscribing to the service of the presentinvention, that is, the subscriber-based ring-back sound service, atstep S301, information indicating that a corresponding applicant (thatis, a phone number of the applicant) is subscribed to the ring-backsound service in response to the request is stored in the subscriberdatabase 80. In addition, subscription information (including the phonenumber) is sent to the HLR 10 from the database 80 at step S302.Therefore, the information indicating that the applicant is subscribedto the service of the present invention is set in correspondingsubscriber profile of the HLR 10 at step S303. Further, new subscriberinformation, including a phone number of a new subscriber, the type ofring-back sound selected by the subscriber and the like, is sent fromthe database 80 to the IP server 70 when the applicant subscribes to theservice at step S304. The IP server 70 assigns a code of the selectedring-back sound in connection with the phone number of the newsubscriber on the basis of the received new subscriber information atstep S305.

Meanwhile, if information, specifying ring-back sounds to transmitdifferent ring-back sounds according to originators, originator groups,and call originating time slots with respect to the correspondingterminating subscriber, is included in the new subscriber information atstep S305, the IP server 70 assigns ring-back sound codes differentlyaccording to classified items.

Thereafter, if any location registration request message (RegistrationNotification) is received from the T_MSC 32 at step S306, the HLR 10determines whether the location registration request is received from asubscriber to the service of the present invention (that is, whether aterminal requesting the location registration is subscribed to theservice of the present invention) by checking the subscriber profile atstep S307. If the location registration request is not received from asubscriber, the HLR 10 sends only a response message to the locationregistration to the T_MSC 32 at step S308-1. On the contrary, if thelocation registration request is received from a subscriber, the HLR 10includes the service setting information of the present invention androuting information to the IP 50 (for example, a number for enabling theT_MSC 32 to perform routing to the IP 50: RoutingDigits) in the responsemessage to the location registration, and sends the response message tothe T_MSC 32, thus enabling the T_MSC 32 to have the service settinginformation and the routing information at step S308-2.

An embodiment of a method of sending the service setting information isdescribed below. As shown in FIG. 7, a reserve field of an additionalservice parameter (CallingFeatureIndicator2) is used as a ring-back tonefield (Specific RingBackTone: SRBT), which is represented by 2-bit data.For example, data “10” indicates that a corresponding terminal issubscribed to the service, but the service is not activated, and data“11” indicates that a corresponding terminal is subscribed to theservice and the service is activated. Such service setting informationis included in the response message to the location registration, whichis sent from the HER 10 to the T_MSC 32.

For reference, a VMSB field, a VMSU field, a VMSNA field, an FMSNAfield, an FMSB field, an FMSU field, an MC field, a CC field, and anMUDN field of FIG. 6 indicate additional services represented by 2-bitdata, respectively. The above fields indicate a Voice Mail Service Busystate, a Voice Mail Service Busy Unconditional state, a Voice MailService Busy No Answer state, a Fax Mail Service No Answer state, a FaxMail Service Busy state, a Fax Mail Service Unconditional state, aMulti-Call state, a Conference Call, and a Multiple Unit DirectoryNumber, respectively.

FIG. 4 is a flowchart showing a service change/addition procedure in thesubscriber-based ring-back sound service method according to the presentinvention.

As described above, if a subscriber subscribed according to theprocedure of FIG. 3 accesses the designated Web server 100 using aPersonal Computer (PC) or the like, the Web server 100 provides a Webpage in which information can be changed/added with respect to theservice of the present invention to a screen of the PC.

Therefore, if the subscriber enters his or her phone number through theWeb page, and then requests the Web server 100 to change a ring-backsound by selecting one from a list of a plurality of ring-back soundsprestored in the IP 50 at step S401, the Web server 100 requests the IPserver 70 to change the ring-back sound at step S402. The IP server 70deletes the code of a ring-back sound, set before in connection with thesubscriber (phone number), according to the request, and stores the codeof the newly selected ring-back sound in connection with the subscriber,thus transmitting the selected ring-back sound to an originator placinga call to the subscriber, instead of a typical ring-back tone, at stepS403.

In the meantime, if the subscriber requests the Web server 100 to add aring-back sound by attaching a voice message file, a logo file or aspecific music file personally produced or obtained by the subscriber tohis or her phone number and sending the phone number with the fileattached thereto to the Web server 100 after selecting a ring-back soundaddition through the Web page at step S404, the Web server 100 requeststhe IP 50 to add the ring-back sound at step S405. The IP 50 obtains theattached file as an additional ring-back sound according to the requestat step S406. Simultaneously, the IP server 70 controls the code of theadditional ring-back sound to be linked to the corresponding subscriberphone number at step S407.

FIG. 5 is a flowchart showing a service cancellation procedure in thesubscriber-based ring-back sound service method according to the presentinvention.

If any cancellation request is received from the subscriber to theservice of the present invention, that is, the subscriber-basedring-back sound service, at step S501, the subscriber database 80 isupdated to allow the subscription of the requesting subscriber (thephone number of the requesting subscriber) to be canceled according tothe cancellation request. In addition, cancellation information(including the phone number) is sent from the database 80 to the HLR 10at step S502. The HLR 10 updates corresponding subscriber profile sothat the subscriber cancels the service at step S503. Further, thecancellation information including the phone number of the cancelingsubscriber (that is, subscriber deletion information) is sent from thedatabase 80 to the IP server 70 when the subscriber cancels the serviceat step S504. The IP server 70 deletes the ring-back sound code assignedat step S305 on the basis of the received cancellation information atstep S505.

FIG. 6 is a flowchart of a method of managing a trunk to provide aring-back sound in the subscriber-based ring-back sound service methodaccording to the present invention. In this case, the trunk managementmethod is an actual service procedure performed after the procedures ofFIG. 3 and/or FIG. 4 are completed.

If an arbitrary originator requests a call connection by dialing aservice subscriber of the present invention (hereinafter, referred to asterminating subscriber), a corresponding 0_MSC 31 requests terminatinglocation information from the HLR 10 (location request) at step S601.

The HLR 10 requests routing information from the T_MSC 32 in response tothe request (Touting request) at step S602. Therefore, the T_MSC 32responds to the request by providing the routing information (that is,TLDN) to the HLR 10 at step S603.

The HLR 10 responds to step S601 by sending the routing information tothe O_MSC 31 at step S604. Therefore, the O_MSC 31 requests an ISUP callconnection from the T_MSC 32 on the basis of the routing information,thereby establishing a traffic channel between the O_MSC 31 and theT_MSC 32 at step S605.

Then, the T_MSC 32 checks the service setting information of the presentinvention stored therein (the information received and stored at stepS308-2 of FIG. 3 and indicated in the SRBT field of FIG. 7). That is, ifthe SRBT field indicates “11”, the T_MSC 32 recognizes that a terminatoris a service subscriber of the present invention and the service isactivated. Therefore, the T_MSC 32 requests the connection of an ISUPcall from the IP 50 on the basis of the routing information received andstored at step S308-2 of FIG. 3, thereby establishing a traffic channelbetween the T_MSC 32 and the IP 50, and, simultaneously, providing theterminating and originating phone numbers to the IP 50 at step S606.According to the result of step S606, trunk channels are establishedamong the O_MSC 31, the T_MSC 32 and the IP 50.

The IP 50 requests a ring-back sound code from the IP server 70 on thebasis of the received terminating and originating phone numbers at stepS607. The IP server 70 responds to step S607 by searching for aring-back sound code designated in connection with the receivedterminating and originating phone numbers according to the request, andsending the searched ring-back sound code to the IP 50 at step S608. TheIP 50 transmits a ring-back sound corresponding to the ring-back soundcode to the originator through the established trunk instead of aprogress tone and a typical ring-back tone at step S609.

If the terminating subscriber answers the call while the correspondingring-back sound is transmitted instead of the ring-back tone asdescribed above and then the T_MSC 32 recognizes the answer of theterminating subscriber, the T_MSC 32 requests the release of the ISUPcall from the IP 50 to allow the IP 50 to release the call at step S610.Simultaneously, the T_MSC 32 enables telephone conversation between theoriginator and the terminating subscriber through the traffic channelestablished between the T_MSC 32 and the O_MSC 31 at step S611.

Further, in order to prevent the occurrence of a situation in which theterminating subscriber is out of a service area to be incapable ofanswering paging (No Page Response: NPR) or incapable of receiving thepaging (No Answer NA) while the corresponding ring-back sound istransmitted instead of the ring-back tone as described above at stepS610, the T_MSC 32 and the IP 50 can be operated in the followingmanner. That is, even though the T_MSC 32 does not recognize the answerof the terminating subscriber like the above case, the T_MSC 32 requeststhe release of the connected ISUP call from the IP 50 if a firstpredetermined period of time has elapsed from the time when it isrecognized that the corresponding ring-back sound is provided to theoriginator, thereby releasing the ISUP call at step S612. Further, atstep S612, even though a request for the release of the ISUP call is notreceived from the T_MSC 32, the IP 50 requests the release of theconnected ISUP call from the T_MSC 32 after a second predeterminedperiod of time has elapsed from the time when the ring-back sound beginsto be provided, thus releasing the ISUP call.

That is, the request for the ISUP call release at-step S610 is requiredfor a call release procedure from the T_MSC 32 to the IP 50 when theterminating subscriber answers the call while the ring-back sound isprovided. At this time, if the terminating subscriber cannot answer thecall for a certain period of time due to the NPR or NA, the T_MSC 32requests the ISUP call release from the IP 50 depending on a presettimer value (that is, the first predetermined period of time).

Generally, the first predetermined period of time is set to 40 to 50seconds, but it may differ according to MSCs. Therefore, the IP 50 mustcontinuously play and transmit the corresponding ring back sound for thecertain period of time before receiving the request message for the ISUPcall release from the T_MSC 32. Further, the request for the ISUP callrelease at step S612 is required for a call release procedure when arequest message for the ISUP call release transmitted from the T_MSC 32is lost, or when the timer value, the first predetermined period oftime, is set to be long in a corresponding MSC to occupy the ISUP callwith the IP 50 for a long period of time. At this time, if the requestmessage for the ISUP call release is not received from the T_MSC 32within the second predetermined period of time, the IP 50 sends therequest message for the ISUP call release to the T_MSC 32 when thesecond predetermined period of time has elapsed.

The first and second predetermined period of times are set inconsideration of a ring-back tone transmission time preset in the T_MSC32 and a length of a ring-back sound. Preferably, the length of aring-back sound represents the average length of all ring-back sounds,and the second predetermined period of time is set to be equal to orlonger than the first predetermined period of time.

In the mean time, the subscriber-based ring-back sound service methodaccording to the present invention enables a terminating subscriber toaccess the HLR 10 to change the service setting information of thepresent invention set in the SRBT field of the HLR 10. For example, whenthe terminating subscriber presses a specific key through his or hermobile terminal, the key information is sent to the HLR 10. The HLR 10can change the 2-bit data indicated in the SRBT field on the basis ofthe key information. However, since an upper bit of the 2-bit dataindicates whether a terminator is subscribed to the service of thepresent invention, it is set not to be changed. Further, since a lowerbit thereof indicates whether the service is activated, it is set to bechanged. That is, in the case of the subscriber, two types of data “10”and “11” may exist as data indicated in the SRBT field. Data “10”represents the inactivation of the service, and data “11” represents theactivation of the service. At this time, the terminating subscriber canfreely change the data from “10” to “11”, or from “11” to “10” dependingon the selection of the specific key. Therefore, the terminatingsubscriber can determine whether to use the typical ring-back tone as itis, or to use a selected ring-back sound instead of the progress tone orthe typical ring-back tone, at the subscriber's own will.

Therefore, if data “10” is indicated in the SRBT field, the T_MSC 32provides the typical ring-back tone to the originator even though theterminator is the service subscriber.

—Ring-Back Sound Query Method—

Hereinafter, a method of querying a ring-back sound in thesubscriber-based ring-back sound service according to a preferredembodiment of the present invention will be described in detail withreference to the attached drawings.

FIG. 8 is a flowchart of a conventional subscriber-based ring-back soundservice method using an originating mobile switching center previouslyproposed by the present applicant This service method is disclosed inKorean Patent Application No. 10-2002-0047212 (9, Aug. 2002). For easeof understanding of the present invention, the construction andoperation of the conventional service method is described in brief.

First, if an arbitrary originator requests a call connection by dialinga subscriber of the subscriber-based ring-back sound service(hereinafter, referred to as a terminating subscriber), a corresponding0_MSC 31 requests terminating location information from a HLR 10(location request) at step S801.

The HLR 10 requests routing information from a T_MSC 32 in response tothe request (routing request) at step S802. The T_MSC 32 responds to therouting request by providing the routing information (that is, TLDN) tothe HLR 10 at step S803.

The HLR 10 responds to the step S201 by sending the routing informationto the O_MSC 31. In this case, the HLR 10 determines whether acorresponding terminator is a service subscriber (that is, whether aterminating terminal is subscribed to the ring-back sound service) bychecking subscriber profile when responding at step S804. Thereafter, ifthe terminator is not a subscriber, the HLR 10 includes only TLDNinformation in a response message to the terminating locationinformation request and sends the response message to the O_MSC 31 inthe same manner as the conventional service method at step S805-1. Onthe contrary, if the terminator is a subscriber, the HLR 10 includesboth service setting information and routing information to theintelligent peripheral 50 (for example, a number enabling the O_MSC 31to perform routing to the intelligent peripheral 50: RoutingDigits) in aresponse message, and sends the response message to the O_MSC 31 at stepS805-2.

The O_MSC 31 may request the connection of a trunk (or designated asISUP) call from only the T_MSC 32 on the basis of the response messageprovided from the HLR 10 according to the results of step S805-1 orS805-2, thereby establishing a traffic channel between the O_MSC 31 andthe T_MSC 32 at step S806. Alternatively, the O_MSC 31 selectively andsimultaneously may request the connection of an ISUP call from theintelligent peripheral 50, thus establishing a traffic channel betweenthe O_MSC 31 and the intelligent peripheral 50 at step S807.

Then, if the traffic channel is established between the O_MSC 31 and theintelligent peripheral 50 at step S807, the intelligent peripheral 50queries and requests a ring-back sound code from the intelligentperipheral server 70 on the basis of terminating and originating phonenumbers at step S808. The intelligent peripheral server 70 responds tothe step S808 by searching for the ring-back sound code preset inconnection with the originating and terminating phone numbers inresponse to the request and sending the searched ring-back sound code tothe intelligent peripheral 50 at step S809. The intelligent peripheral50 transmits a ring-back sound corresponding to the received ring-backsound code instead of the ring-back tone to the originator through thetraffic channel at step S810.

Finally, if the terminating subscriber answers the call while thering-back sound is transmitted instead of the ring-back tone asdescribed above and then the O_MSC 31 recognizes the answer of theterminating subscriber, the O_MSC 31 requests the release of the ISUPcall from the intelligent peripheral 50 to allow the intelligentperipheral 50 to release the call at step S811. Simultaneously, theO_MSC 31 enables telephone conversation between the originator and theterminating subscriber through the traffic channel established betweenthe T_MSC 32 and the O_MSC 31 at step S812.

FIG. 2 is a block diagram of the subscriber-based ring-back soundservice apparatus to which the subscriber-based ring-back sound servicemethod according to the present invention is applied. FIG. 2 is a blockdiagram of a subscriber-based ring-back sound service apparatus to whicha subscriber-based ring-back sound service method according to thepresent invention is applied. As shown in FIG. 2, the service apparatusincludes a Home Location Register (HLR) 10; Mobile Switching centers(O_MSC/VLR and T_MSC/VLR) 31 and 32 communicating with the HLR 10through a Signaling Transfer Protocol (STP)-based No. 7 network 20; anIntelligent Peripheral (IP) 50 connected to the No. 7 network 20 througha gateway (CGS) to communicate with both the O_MSC/VLR 31 and theT_MSC/VLR 32 through the gateway 40; an IP server 70 for performing datacommunication with the IP 50 through the Internet 60; a subscriberdatabase 80 connected to the HLR 10 through the Internet 60; and a Webserver 100 connected to the Internet 60 through a gateway 90 tocommunicate with both the IP 50 and the IP server 70.

The HLR 10 has all the functions of a conventional network component,and additionally has a function of presetting and storing firstinformation indicating whether a ring-back tone is substituted andsecond information for performing routing to the IP 50 as profileinformation of a terminating subscriber. The profile information ispreset and stored as additional service subscription information of theterminating subscriber profile.

The MSCs 31 and 32 have all the functions of the conventional networkcomponents, and additionally have functions of receiving and storing thepreset first and second information while communicating with the HLR 10at the time of registering the location of the terminating subscriber,receiving a ring-back sound for substituting for a typical ring-backtone while communicating with the IP 50 on the basis of the first andsecond information when a call connection to the terminating subscriberis requested, and providing the received ring-back sound to acorresponding originator instead of the ring-back tone. As anotherexample (according to the method of FIG. 8), each of the MSCs 31 and 32has functions of requesting a call connection from a corresponding T_MSCsimilar to the conventional method, and, simultaneously, requesting acall connection from the IP 50 on the basis of the first and secondinformation included in a terminating location information responsemessage, if receiving the terminating location information responsemessage from the HLR 10 while functioning as an O_MSC.

In the subscriber-based ring-back sound service method as shown in FIGS.1 and 8, the IP 50 is generally characterized in that it stores avariety of ring-back sounds therein, and it is connected to the MSCs 31and 32 through the gateway 40 to provide the stored ring-back sounds tothe MSCs 31 and 32 while communicating therewith. However, in thepresent invention, the IP 50 is further characterized in that severalIPs are locally dispersed to allow each IP to be directlytrunk-connected to one or more adjacent MSCs on the basis of singularrouting information without passing through a gateway (refer to a laterdescription of FIG. 9). For these operations, each IP 50 storesring-back sounds of all subscribers to correspond to codes.Additionally, the IP 50 identifies routing information to one of aplurality of IP servers on the basis of the information of a terminatingsubscriber provided from the trunk-connected corresponding MSC. In thiscase, the plurality of IP servers are classified according to phonenumbers of subscribers, prefix numbers thereof, prefix number groupsthereof, or main working areas of subscribers. Then, the IP 50 performsrouting to the corresponding IP server on the basis of the identifiedrouting information, and thereafter queries and obtains a code of aring-back sound on the basis of the information of the terminatingsubscriber.

The IP server 70 has a function of communicating with the IP 50 throughthe Internet 60 to specify the types of ring-back sounds, which the IP50 must provide to the MSCs 31 and 32, on the basis of the combinationsof identification information of terminating subscribers requested toconnect calls, identification information of originators correspondingthereto and/or time slot information when call connections arerequested. For example, various types of ring-back sounds can bespecified according to originator, originator group, originator age,gender, occupation, and/or call originating time slot. For example, whenthe IP server 70 assigns respective codes to various ring-back soundsstored in the IP 50, and a terminator selects originators, originatorgroups, call originating time slots, etc., when subscribing to theservice or changing his or her information, and specifies ring-backsounds corresponding to the selected items, the IP server 70 has aplurality of pieces of information on the specified ring-back sounds inthe form of a table. In this state, the IP server 70 provides codeinformation of a subscriber, queried by the IP 50, to the IP 50, thusenabling a ring-back sound corresponding to the code to be provided tothe MSC 32.

The Web server 100 is connected to the IP 50 or the IP server 70 throughthe Internet 60 to add a ring-back sound to the IP 50, or changeinformation (specific originator, originator group, call originatingtime slot, etc.) required to specify ring-back sounds by the IP server70 and ring-back sound codes corresponding thereto. Such an addition andchange function can be performed by the subscriber through a Web pageprovided from the Web server 100.

FIG. 9 is a view showing an example of a network connection among theMSCs 31 and 32, the IP 50 and the IP server 70 of FIG. 2. As shown inFIG. 9, the IP 50, that is, IP #n, IP #(n+1), IP #(n+2) and IP #(n+3)are locally dispersed to allow one or more adjacent MSCs to be directlytrunk-connected to each IP on the basis of singular routing information.The IP #n, IP #(n+1), IP #(n+2) and IP#(n+3) locally dispersed in thisway identify routing information to one of the IP server 70, that is, IPserver #n and IP server #(n+1), for example, installed in the center ofa service area, on the basis of the information of terminatingsubscribers provided from trunk-connected MSCs 31 and 32.

In this case, the IP servers are classified according to the phonenumbers of subscribers, prefix numbers thereof, prefix number groupsthereof, or main working areas of subscribers by a system operator.Then, the IP 50 performs routing to the corresponding IP server 70 (oneof the IP server #n and the IP server #(n+1)), through the Internet 60on the basis of the identified routing information, thus querying a codeof a ring-back sound.

FIG. 10 is a flowchart of a method of querying a ring-back sound in thesubscriber-based ring-back sound service method according an embodimentof the present invention. For convenience of description, it is premisedthat a plurality of pieces of routing information from the IP 50 to theIP server 70 are classified according to prefix numbers of subscribersamong the phone numbers of subscribers, prefix numbers thereof, prefixnumber groups thereof, or main working areas of the subscribers.

First, if the O_MSC 31 requests an ISUP call connection from the IP 50(that is, one of the IP #n, IP #(n+1), IP #(n+2) and IP #(n+3) of FIG.9) located close to the O_MSC 31 or the T_MSC 32 to establish a trunkchannel between the O_MSC 31 and the IP 50, as in the case of steps S106of

FIG. 1 and S807 of FIG. 8, at step S1001, the IP 50 searches a firstdatabase thereof, in which pieces of routing information to the IPserver 70 are classified and stored according to prefix numbers ofsubscribers as shown in FIG. 11, for routing information correspondingto a prefix number of a terminating subscriber on the basis of a phonenumber of the terminating subscriber provided at step S1001. At thistime, if the phone number of the terminating subscriber is “293-xxxx”,the IP 50 identifies and searches for routing information correspondingto the prefix number “293”, that is, routing information to the IPserver #n, at step S1002.

The IP 50 performs routing to the IP server 70, that is, IP server #n,according to the identified routing information, and then queries the IPserver 70 about a ring-back sound code and requests the ring back soundcode, on the basis of the phone number information of the terminatingsubscriber at step S1003.

The IP server 70 (IP server #n) searches a database thereof, in which aplurality of pieces of code information are stored in connection withsubscriber phone numbers as shown in FIG. 12, for a ring-back sound code“07” corresponding to the phone number of the terminating subscriber“293-xxxx” in response to the request at step S1003 at step S1004. TheIP server 70 responds to step S1003 by sending the searched ring-backsound code “07” to the IP 50 at step S1005.

The IP 50 searches a second database thereof, in which ring-back soundcodes and ring-back sounds are stored to correspond to each other asshown in FIG. 13, for a ring-back sound #7 corresponding to thering-back sound code “07” received at step S1005 at step S1006. The IP50 transmits the ring-back sound #7 instead of the ring-back tone to acorresponding originator through a traffic channel established betweenthe O_MSC 31 and the IP 50 at step S1007.

—Ring-Back Sound Ascertainment Method—

Hereinafter, a method of ascertaining a ring-back sound in thesubscriber-based ring-back sound service according to a preferredembodiment of the present invention will be described in detail withreference to the attached drawings.

The service apparatus of FIG. 2 is used as an apparatus for implementingthe ring-back sound ascertainment method of the present invention.Therefore, since a description of the construction and operation of theservice apparatus of FIG. 2 is the same as that of the above-describedtrunk management method, it is omitted.

FIG. 14 is a view showing the basic construction of an apparatus forimplementing the ring-back sound ascertainment method in thesubscriber-based ring-back sound service according to an embodiment ofthe present invention. In this case, since the ring-back soundascertainment method is implemented on the basis of the serviceapparatus of FIG. 2, the same reference numerals are used throughoutFIGS. 2 and 14 to designate the same or similar components.

As shown in FIG. 14, the apparatus includes MSCs 31 and 32 which arenodes of a mobile communication network; the IP server 70; and anAutomatic Response Service (ARS) unit 55. The ARS unit 55 has a varietyof ring-back sounds to correspond to code information, the same as theIP 50 of FIG. 2. Further, the ARS unit 55 obtains designated information(for example, an originating phone number of a corresponding subscriberwhich is information of the subscriber that uses a ring-back sound to beheard) while communicating with mobile terminals (not shown) ofsubscribers connected to the ARS unit 55 through the MSCs 31 and 32depending on a preset ARS scenario. Further, the ARS unit 55authenticates the connected subscribers according to the obtainedinformation, and requests and obtains a desired code from the IP server70 while communicating with the IP server 70 through the Internet 60.Moreover, the ARS unit 55 requests the IP server 70 to change the codesof the connected subscribers depending on the selection of the connectedsubscribers based on the scenario.

FIG. 15 is a flowchart of the method of ascertaining a ring-back soundin the subscriber-based ring-back sound service according to theembodiment of the present invention. Since the ring-back soundascertainment method is applied to the apparatus of FIG. 14, it isdescribed in parallel to the operation of the apparatus.

If a first subscriber's mobile terminal (not shown) is connected to theARS unit 55 through an originating MSC 31 or 32 (hereinafter, it ispremised that the originating MSC is the O_MSC 31) at step S1501, theARS unit 55 makes queries on the basis of a preset scenario, and thefirst subscriber answers the queries through the input of a key on themobile terminal or another means at step S1502. Through such aquery/answer procedure, the ARS unit 55 obtains phone number informationof an arbitrary second subscriber (the second subscriber may be the sameas the first subscriber), selectively input from the first subscriber'smobile terminal, as preset required information, and, simultaneously,obtains an originating phone number from the first subscriber's mobileterminal, that is, the phone number of the first subscriber's mobileterminal, at step S 1503.

For example, the ARS unit 55 obtains the originating phone numberprovided from the O_MSC 31, that is, the phone number of the firstsubscriber's mobile terminal, simultaneously with the connection to thefirst subscriber's mobile terminal at step S1501. Additionally, the ARSunit 55 sends a voice message, such as “please enter a subscriber'sphone number using a ring-back sound that you want to ascertain”, to thefirst subscriber's mobile terminal at step S1502. If the firstsubscriber hears the voice message received through his or her mobileterminal and enters the phone number of the second subscriber's mobileterminal using keys according to the voice message, the ARS unit 55receives and obtains the phone number information entered using keys atstep S1503.

Then, the ARS unit 55 requests a corresponding ring-back sound code fromthe IP server 70 by querying the code information corresponding to thephone number information of the second subscriber, on the basis of thephone number information of the second subscriber among the phone numberinformation of the first and second subscribers obtained at step S1503.

The IP server 70 responds to the request of step S 1504 by searching thedatabase thereof constructed as shown in FIG. 16 for code informationstored to correspond to the phone number of the second subscriber inresponse to the request, and providing the searched code information tothe ARS unit 55 at step S1505. For example, if the second subscriber'sphone number is “293-xxxx”, the IP server 70 provides code information“07” stored to correspond to the phone number to the ARS unit 50.

The ARS unit 55 searches the database thereof constructed as shown inFIG. 17 for a ring-back sound #7 as a ring-back sound stored tocorrespond to the code information “07” on the basis of the codeinformation “07” provided from the IP server 70 at step S1505, andtransmits the searched ring-back sound #7 to the first subscriber'smobile terminal through the MSC 31 to enable the first subscriber tohear the ring-back sound #7 at step S1506. Therefore, the firstsubscriber can ascertain the ring-back sound of the second subscriber.

While the ring-back sound #7 is transmitted as in the case of step S1506or after the transmission has been completed through the repetitionthereof for a preset period of time or by a preset number, the ARS unit55 determines whether a request for the change of the ring-back sound isreceived from the first subscriber's mobile terminal at step S1508,through a query/answer procedure with the first subscriber's mobileterminal based on the scenario at step S1507.

For example, if a specific key for changing a ring-back sound isselected by the first subscriber's mobile terminal at step S1507 whilethe ring-back sound #7 is transmitted at step S1506, the ARS unit 55determines that the ring-back sound change request is received at stepS1508. Alternatively, if the ARS unit 55 sends a voice message, such as“press number “1” if you want to change a ring-back sound, and pressnumber “2” if you finish this service”, to the first subscriber's mobileterminal after the transmission of the ring-back sound #7 has beencompleted through the repetition thereof for a preset period of time orby a preset number, and then a key of the number “1” is selected by thefirst subscriber's mobile terminal in response to the voice message, theARS unit 55 also determines that the ring-back sound change request isreceived at step S1508.

If determining that the ring-back sound change request is received atstep S1508, the ARS unit 55 requests the IP server 70 to change aring-back sound code on the basis of the first subscriber's phone number(for example, 294-0000) and the second subscriber's phone number (forexample, 293-xxxx), obtained at step S1503, at step S1509.

The IP server 70 changes code information “17”, stored in the databasethereof to correspond to the first subscriber's phone number “294-0000”,to code information “07”, stored to correspond to the secondsubscriber's phone number “293-xxxx” according to the request at stepS1509 and stores the changed code information in the database as shownin FIG. 16. That is, the code information stored to correspond to thesubscriber's phone number “294-0000” is changed from “17” to “07” atstep S1510.

As a result of step S1510, a ring-back sound, a substitute for a typicalring-back tone, transmitted when an originator places a call to thefirst subscriber, is changed from the ring-back sound #17 correspondingto the previous code “17” to the ring-back sound #7 corresponding to thenew code “07”, as shown in FIG. 17. That is, the first subscriber setsthe ring-back sound heard at step S1506 to his or her new ring-backsound.

Meanwhile, if determining that the ring-back sound change request is notreceived at step S1508, the ARS unit 55 determines whether “finish” isselected at step S1511. If it is determined that “finish” is selected,the ARS unit 55 finishes the entire process at step S1512.

Further, when the ARS unit 55 is trunk-connected to the MSC 31 at stepS1501, the ARS unit 55 authenticates the first subscriber on the basisof the phone number of the first subscriber's mobile terminal, which isthe originating phone number provided from the MSC 31. Further, the ARSunit 55 can determine whether to perform a procedure after step S1501according to the authenticated results.

INDUSTRIAL APPLICABILITY

As described above, the present invention provides a trunk managementmethod to provide a ring-back sound in a subscriber-based ring-backsound service, which prevents muting which may occur due to a differencebetween a time period for transmitting a typical ring-back tone andpreset in a mobile switching center, and a time period for playing aring-back sound stored in an intelligent peripheral, a No Page Response(NPR) state, No Answer (NA) state or the like.

According to a ring-back sound query method sound in a subscriber-basedring-back sound service of the present invention, there are advantagesin that respective intelligent peripherals are locally dispersed andinstalled close to mobile switching centers without passing through agateway, thus saving trunk resources between mobile switching centersand intelligent peripherals, preventing mobile switching centers fromexcessively occupying trunk resources, and promptly transmitting aring-back sound instead of a typical ring-back tone.

Further, according to the ring-back sound ascertainment method in asubscriber-based ring-back sound service of the present invention, thereare advantages in that a subscriber can ascertain his or her ownring-back sound or another subscriber's ring back sound withoutunnecessarily occupying trunk resources or without placing a call, andset the ascertained ring-back sound to his or her new ring-back sound.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

1. A method of managing a trunk to provide a ring-back sound in asubscriber-based ring-back sound service, the ring-back sound servicemethod including the steps of a) a home location register providingfirst information indicating whether a ring-back tone preset in the homelocation register is substituted and second information for performingrouting to intelligent peripheral means to a corresponding terminatingmobile switching center when a location of a terminating subscriber isregistered; b) the terminating mobile switching center providing aring-back tone to an arbitrary originator or requesting a connection ofa trunk call from the intelligent peripheral means according to thefirst and second information, when the terminating mobile switchingcenter recognizes a call connection request transmitted from thearbitrary originator to the terminating subscriber, c) the intelligentperipheral means searching for a ring-back sound preset with respect tothe terminating subscriber after connecting the trunk call in responseto the trunk call connection request, and providing the searchedring-back sound to the originator instead of the ring-back tone throughthe trunk-connected terminating mobile switching center, the trunkmanagement method comprises the steps of: The terminating mobileswitching center requesting a release of the connected trunk call fromthe intelligent peripheral means when an answer of the terminatingsubscriber is recognized or when a first predetermined period of timehas elapsed from a time when it is recognized that the searchedring-back sound is provided to the originator, and The intelligentperipheral means requesting a release of the connected trunk call fromthe terminating mobile switching center when a second predeterminedperiod of time has elapsed from a time when the ring-back sound beginsto be provided:
 2. The trunk management method according to claim 1,wherein the first and second predetermined period of times are set inconsideration of a ring-back tone transmission time preset in theterminating mobile switching center, and a length of the ring-backsound.
 3. The trunk management method according to claim 2, wherein thelength of the ring-back sound is an average length of all ring-backsounds.
 4. The trunk management method according to claim 1, wherein thesecond predetermined period of time is set to be equal to or longer thanthe first predetermined period of time.
 5. A method of querying aring-back sound in a subscriber-based ring-back sound service, in whichrouting from at least one intelligent peripheral to at least oneintelligent peripheral server is performed to query a ring-back sound ina subscriber-based ring-back sound service process, the intelligentperipheral being constructed in such a way that a plurality ofintelligent peripherals are installed according to mobile switchingcenters or mobile switching center groups to allow one or more adjacentmobile switching centers to be directly trunk-connected to one of theintelligent peripherals according to singular routing information, andthe intelligent peripheral server being constructed in such a way thatring-back sound codes corresponding to ring-back sounds stored in theintelligent peripherals are stored in the intelligent peripheral serverto be preset and registered according to subscribers, and a plurality ofintelligent peripheral servers are installed according to phone numbersof subscriber terminals, prefix numbers thereof, prefix number groupsthereof, or main working areas of the subscribers to correspond toinformation of the subscribers, the method comprising the steps of a)when a request for a trunk call connection that allows a ring-back soundpreset and registered with respect to a terminating terminal to betransmitted to an originating terminal instead of a typical ring-backtone according to routing information to a corresponding intelligentperipheral provided from the home location register, is received from acorresponding mobile switching center, the corresponding intelligentperipheral searching for routing information to one among the pluralityof intelligent peripheral servers depending on information of theterminating subscriber provided from the trunk-connected correspondingmobile switching center; and b) the corresponding intelligent peripheralperforming routing to the corresponding intelligent peripheral serverdepending on the searched routing information and querying and obtaininga code of a corresponding ring-back sound depending on the informationof the terminating subscriber.
 6. The ring-back sound query methodaccording to claim 5, wherein each of the intelligent peripherals hasring-back sounds of all subscribers to correspond to the codes.
 7. Thering-back sound query method according to claim 5, wherein each of theintelligent peripherals and each of the intelligent peripheral serverscommunicate with each other through Internet protocol.
 8. The ring-backsound query method according to claim 5, wherein the information of theterminating subscriber is a phone number thereof
 9. A method ofascertaining a ring-back sound in a subscriber-based ring-back soundservice, which allows a subscriber to ascertain his or her own ring-backsound or another subscriber's ring-back sound substituting for a typicalring-back tone using an automatic response service unit having a varietyof ring-back sounds as specific sounds to correspond to code informationwhen the subscribed-based ring-back sound service for providing aterminating subscriber's desired specific sound instead of the ring backtone is implemented, the automatic response service unit performing thesteps of: a) obtaining information of an arbitrary second subscriberusing a ring-back sound to be ascertained while communicating with amobile terminal of a first subscriber connected to the automaticresponse service unit through a mobile communication network dependingon a preset scenario; b) requesting and obtaining code informationcorresponding to the second subscriber information from an intelligentperipheral server while communicating with the intelligent peripheralserver having the code information to correspond to the subscriberinformation; and c) transmitting a ring-back sound provided tocorrespond to the obtained code information to the mobile terminal ofthe first subscriber.
 10. The ring-back sound ascertainment methodaccording to claim 9, further comprising the step of d) changing codeinformation corresponding to the first subscriber information to codeinformation corresponding to the second subscriber information whilecommunicating with the intelligent peripheral server, when a request forchange of the transmitted ring-back sound is received from the mobileterminal of the first subscriber depending on the scenario.
 11. Thering-back sound ascertainment method according to claim 9 or 10, whereinthe subscriber information is a phone number of a mobile terminal ofeach subscriber.
 12. The ring-back sound ascertainment method accordingto claim 9 or 10, further comprising the step of authenticating thefirst subscriber depending on an originating number from the mobileterminal of the first subscriber.
 13. The ring-back sound ascertainmentmethod according to claim 9, wherein the automatic response service unitand the intelligent peripheral server communicate with each otherthrough the Internet.